Physical Chemistry

Physical chemistry

Le Chatelier Simplified

I remember when I was taught this, that the only definition we were given was Le Chatelier’s actual definition, or his principle, and I remember reading that language and going geez, that’s really hard to follow as a student, so I used to always try and present that and then break it down in to a more simple sort of version that I thought would be easier to understand.

Le Chatelier's principle

I was thinking about Le Chatelier’s principle and how that’s quite cumbersome in its wording, and so when I teach it, and how I always break that down into language that’s probably easier for students to understand, and Bob tells me that’s called repackaging, and I sort of thought that through all my teaching I do a fair bit of repackaging, a lot of the time, so I guess that was just a trait that I use and has been pretty successful for me, I think.

Strong and Weak Acids

Students from high school might understand that vinegar for example is a weak acid compared to hydrochloric acid, but they never knew why. And you could then show them that with equilibrium, this is why. And all of a sudden they’re, 'oh, I’ve always known that I shouldn’t spill HCL on my hand, but I can spill vinegar on my hand and put it on my fish and chips'... Those sorts of moments can really... the students go ‘oh wow.’


A New Language

Chemistry is a different language so I try to approach it that way by explaining the ideas behind symbols.

Student Definitions of Le Chatelier's Principle

Put a picture of Le Chatelier and the quote of what he said and get them all to write down what they think that means and then let them talk in groups of three and all form a new idea of what they think it means. And then a few lectures later come back and ask them to do it again. Get them to submit their definitions so you can see how their understanding evolves and discuss it in class.

Industrial Processes

Bring in industrial processes. For example, the Bayer process, which is the principal industrial means of refining bauxite to produce alumina (aluminium oxide). Talk about the conditions used for that. So how you can increase the yield of the reaction? The Bayer process is done at high temperatures and high pressures. This demonstrates ways to increase the amount of product.

Self-Darkening Sunglasses

Integrate applications of equilibrium along the way to draw back students' interest. For example, glasses that darken to sunglasses.

YouTube Demonstrations

Use YouTube demonstrations which demonstrate well (gases etc) but would be difficult to do the real demonstration in a lecture theatre.

Link to YouTube Video: Le Chatelier's Principle

Introduce Equilibrium in Previous Topics

Start to flag the concept of equilibrium early when teaching other topics, saying this is the concept of equilibrium we’ve got to come to later. So students start to understand how it’s all interlinked, rather than it being a lone, odd concept?

Relate to other Subjects/Courses

Compare the material to what they might be learning in physics. For example, in Le Chatelier’s principle, a phrase like ‘counteract the change’ is similar to Lens’s Law in physics for electromagnetic induction. So maybe if students have a better grip of that they can see similarities there. It’s trying to draw that bridge. If the students aren’t doing physics you can always draw something from maths or something from biology.


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